Telephone-exchange system



)dy 114,n 1925.

E. E. CLEMENT 'reunions EXCHANGE SYSTEM Filed, Apm zo, movA f 7 Sheets-Sheet 1 @www l'oz MME Wx July 14, 1925. 1,545,880 Y E. E. CLEMENT TELEPHONE EXCHANGE .SYSTEM med April 2o, mov '/'sheets-sneet 2 Swarm',-

July 14, 1925.

E. E. CLEMENT TELEPHONE vEXCHANGE SYSTEM Filed pril 2o, 19o? '7 Sheets-Sheet 5 July 14, 1925. 1,545,880

. AE. E. CLEMENT TELEPHONE EXCHANGE SYSTEM Filed April 20, 1907 '7 Sheets-Sheet 5 July 14, 1925.

1,545,880 E.E.CLEMENT TELEPHONE EXCHANGE SYSTEM Filed April 20, 190'? 7 Sheets-Sheet 6 *T il July 14, 1925. 1.545.880

E. E. CLEMENT I TELEPHONE EXCHANGE SYSTE nventoz lllllllk Patented July 14,- 1925.

Enwnni) E. cnnivrniiinfcr nIsrRrc'r oncoLUiuiiA,ssrGNon; in?Y ivmsit'n ssreiuusnrs, To frein Non-Tn ELECTRIC Mrefcoi To (fill 'whom t may concern y f y Be it known that l, EnwAR E. C'Lnirnirr; a citizenof the United Stites, residiirr` at lashington,V in thel DistrictV olil Collini iin have invented certain new and useful lmprorein-cnts in Telephone-lilzchangeSysteniss of which the following 1s a specicaticn,

Ahad therein to theacccin l reference being' panyiug drawing.Y

My invention relates to teleijhene esichange systems; and particularly Ato semi# automatic systems in `which automatic switches or their equivalent areI employedV number of lines," and the distribution of the" load, tliat is to say, the incoming calls, among' sets of switching apparatus and among the operators, whereby uniform eticiency in service nia'y be attained. 'i i Fcrfthe salie of snnplicityin `descriptaon I shall specify herein automrttic switches oli thcvtype known as Strowgei selectors and connectors, the constructioii 'otsucli switches being` well shown in- L'etters Paitent No. 815,1@ and No; 81553215 granted to1 l-eith and Erickson, March 13j 1906. l The circuits commonly employed with these switches are well known to those skilled in the art. l shall also specil'y` a. typeol com-` mon battery line circuitsfand central o'iiice talking cii'cuitswhich are considered stand#` ard,1 and generally known'I as two-wire bridged battery circuits. t is t0' b'eun'der# stood however," thatin specifying theaIr-w paratus and circuits inenti'onedth'e types `lorpurposesv ol' tlesci'l not `asy limiting' the invention.

Stated in terms ofthe embodiment thus llare used ptiorn vand presented, the present invention confiprises number of groups of selector and' connector'- switches less-than the number of lines to' be served; anumbei` of primaryk selector' switches normally set baclto a fined or Z'ero positivi.- fud adapted t0' were@ V.the Lcalls i lines with sind groeps; qf sneer@ ne nector switches a numbing'` of operators selective keysV and lmpuls'e transmitting' `means controlled thereby`with automatic' secondary selector switches normally lset y back at a zero or idle Ijoslition, and loting to, connect the trunks Yfrom theprimai-'y selector switches to the operatcrsapparatus when the calls Vare received; whereby the operators may talk with the subf` scribers, an may actuate lthe appropriate selector an"l connector Switches to connect the calling and the wantedlines.'V x f By having all the primtry and secondary selector switches normallyy set back to zero,

Al effect a iinii'orin distributionl comui'er'xcino` always with the first trunk or the first postit1on. When; a subscriber. c'allsiivii,` current in his line energizes a relay. which starts up a? primaryl selector switch', said switch" continuing to' progress step biyst'ebuntil wipers connect the terminals" oi' an idle trunk, at whichI time the cutoff relay ofthe line receives current fr'ofntheswit'chdcir cuit, theV switch stops;` and the secod'ry: selector switch is str'ted `to connect the trunk to an idle oper'ators' circuit; l An propriat'e signaling means such "l a is .provided for each operators circuit; and' the operatorbeing thus aicprisedl of a call is `able to connect lier telephone througli hei" circuit to' the-trunk and the-ncel tothe' call`l in` qljv line,I and afterward to traiisfi'iii'tA impulses i the trunk andforward to rits automatic first selector switch-to secure connection with' the linef'wanted Testing and ringin'gci' the wanted-line are automatic.

' The specific distinguishing, feature ofthe apparatus hereinafter set forth,v is that each' trunk has a terminal selector switch y'.

whichv a subscribers lii`1e` may be connected inT clling to idle truikline leading iV first selector switch; and ,xeach operatofs set f` ispovided .with a switch startingul troni zero or normally operative' position to" select and connect a trunkline with the coin-yl trilling and tink-ing circuit cian dleperd ato'r. l The operators' circuit remains con nec'te'd tothe {muifilr` as long as may b'e'rneces'# sary to send the proper, impulse fr setting d te i'erO,

My invention is illustrated in the accompanying drawings in which- Figure 1 is a dia-gram showing a calling subscribers line and a portion of the centralV office equipment,

Figure 2 is a similar diagram complementary to Figure V1, and. intended to be placed below the latter, showing another portion of the central oinice circuitsV Figure 3 is a similar diagram also compleinentaiy to Figure 1, intended to be placedA at the right of the latter, and showing a selector and connector switch withk their circuits,v through which the callingl line may il O - be connected with anyone of a considerable number of other lines, v l, Figure fl, is a diagram of circuits ccmpleinentary to Figure 2, intendedV to bel Y placed at the right of the latter,

Figure 5, is an .end view of an improved rota-ry selector switch,

Figure 6 is asection on the line X-X.

of Figure 5,

Figure 7 is a similar view with the bank vcontacts removed, of a modification of. the

' and the trunks whereby calls are distributed between the said equipments so that one call. may not operate several switches for connecting operators equipments.

Referring to Figure 1 A is a subscribers stat-ion connected to the central oiiice by line wires 1 and 2 whichY are Inormally connected through the contacts of a cut-ofi relay to the line relay M and the.l ground, respec tively, the line relay being connected to the main battery B through the wire 3.

relay to multiple bank contacts of switches S. Each switch S is a step by step selector and is whatis called a single motion or rotary switch, having a spindle s journalled so that it can turn upon the axis and provided with a ratchet wheel by which it may be turned. by a stop or detent pawl controlled by the electromagnet s2. The mechanical construction of this switch is shown in Figures 5, 6k and 7, which will be hereinafter particu-v larly referred to. The circuit of the electromagnet s2 is controlled by the line relay M through its armature m.l forL which `purpose,

the front contact 7 of the relay is connected by a wire 8 with the magnet s2., while the armature m is connected through an inter-` rupter I with abattery wire 3. This interrupter is continuously operating and may consist, as shown, of a rotative cylinder having alternating insulating and conducting `by any ,suitable means.

yvided with multiple test contacts 11.

Line .extensions 4 and 5 extend from the cut-olf This ratchet wheel is engaged portions, one conductor being connected with the conducting portion and another with a pen bearing upon the cylinder, so that as the cylinder rotates the conductors will be alternately lconnectedtogether and disconnected as the pensuccessively bears upon the conducting and insulating portions. The cylinder is continuously driven With such an ar` rangement it is only necessary to maintain the circuit closed, when the successive energizations and deenergizations of the magnet and vibrations ofl its armature will continue indefinitely. In the present case as the magnet 82, vibrates its armature, it also turns the spindle s by ymeans of its pawl and a ratchet on the spindle, any retrogrademotion ofthe spindle being prevented by the ,stop pawl controlled by the magnet s. The

spindle is provided with a return spring, preferably a coiled spring, which has a constant tendency to turn the'y spindle back against the pawl ofthe magnet s', and when this pawl is released by the energization of this magnet, willr actually turn back the spindle to its normal,` Zero, or inoperative position.` The circuit of the magnet s2 in addition to being controlled by the line relay M, is also controlled by the relay R', of the -trunk while the release magnet s is conf trolled partially by the relay R5.

Inaddition to the bank contacts 9 and 10 to which extensions l and 5 of the subscribers line are connected, each switch'S isfprlp- T e wipers 12 and 18 of the switch are adapted to engage,respectively. with the bank contacts 9 and 10, while a test wiper 14 is adaptedto engage with the bank contacts .111. From the wipers 12 and 13 are trunk eXtensions 15 and 16, the connection of which with the trunk lines 17 and-1S is controlled by a trunk cut-ofi relay N, which is controlled by the relay R.l

The relays R and the two trunk conductors with the main battery between them. The tip relay R is connected at one side with the conductor 17, the other side being grounded, while the sleeve relay R is at one side connected to the free side of thebattery B and at the other side tothe trunk conductor 18. lThe tip relay R responds to the act of the calling subscriberand controls the clearing out of the automatic apparatus; the` sleeve relay becomes energized whenthe switch S picks out an idleitrunk and` then closes the cir* cuits of the magnets R2 and R4 which are respectively the stepping magnet of the secondary or operator selector switch S and a R are bridged between Y i lun ltlli locking relay serving also as a cutlofl' relay for shifting the control as the operators circuit is connected, The functions of these several relays will best appear from the The 'rel'jysj5 and RG are conbined` eutoff and repeating relays". The relay R? when ei'iergized over the operators Wire 19 pulls up its armature, breaks apart the trunk Wires21 and 23 and connects the latter to the `Wire 25 leading tothe free terininai oi? the battery B, so as to send an impulse of Current through the trunk Wire 23. l/Vhen the relay RG is energized over the operators Wire 20 it pulls up its' armature to break apnrt the trunk Wires 22 and 241 and conneets the latter to the Wire 26 which is connected to the free terminal oi' the battery B, thns sending an impulse of Current Vforward over the trunk Wire 24. l/Vhen both of the relays R5 and RG are simultaneously energized; they connect the operators Wires 20 and 19 to the trunk wires 21 and 22, respectively, eo that the operator nitty Connect her telephone to thelwires 21 and 22 and oomrnuniealte 'with the Calling' subscriber. lIt

Will be observed thztt the Wires 21 tndl 22 are,

extensions 'of the trunk Conductors 1,7 and 18,A espetively-.fto Which they are eonneeted by nieans i -eondensers C,- Vthe eondensers beingr proyided to prevent confusion 'ot battery' entrent betiyeen"` the answering* eind calling ends of the trunk section., It will also be seen 'that the onductors 23 ain-d 24 are respectively' eitensins ot the trnl eondhetors 21 and 22'.`

Tltest Contact 14 is connected: by a Wire 27 with e eontact 28 through which circuit isbrolen when' the relay R is energized and,

therefore, when the trunk is in use. When the trunk is not in use, and its switch S lilas been stepped into position to conne'e't it with a calling line connection may be traced freni the Wiper through conductor 27,` contacts 28 and 29,con`ductor 30 and eht-olirelay N to' ground: y A Y It will have been observed that there is'y one switch S forieael trnk, in order ti'culzirly to Figure 8, it will be seen that the conductors 8, k8 and 82 which lead respectively' tothe Steppin?? magnets s2, 152, 2S2 and ete. of the respective seleetor sWitehs" S, 1S, 2s and etc., are Connected together by a condu'etor 31 so that-,the energiz'ation of anyv line relayv M; iM'gor 2M et any siibscribe'rs non will'Y nb'einte in n'nnnnt nne side nii the Ibattery B'iiiiongh @ne intern@,ttiA l with air of the stepping magnet i2 152 and ein. n Win benzina nonne-,tint the ,gebundenenneetions of these stepping ingfnet's are triade' tinnngii fue been contacts of the arinntniejs ai, 11"2`l and ete. oi the7 sleeve reley's R', im, 2? 'and ete; Itwill be obs'eved; how; ever, tht altl'iough the ground connection oi'eoli bij' tl s-'epiing ingn'ets is iii le thioi'i'gli the bahgcoiitct of its partieularly ariiiatre 1, 11" or 2", the 'circuit thus pan iially nitide ini t be completed through thea innen-d nent-niets' ni. nu ni those ernennen at' one side oi the ernia-ture in question. These ini-'mrd contante ni-e only nonnen-ted when their' Controllingr relys are energized andi therefore, only when the trunksk to which they e rresbon'd fire in use. It'vill nnivbb np'pnrnt ninin will be impossible oper'ntion by the seme eall and also thwt the tr'iiiiks Will' beprogres'siy'ely selectedfby sueneeding`A nails.: To ilinstrnte, assuming that 1" the 'only Conneeted with `ground as sjhf'oyvn iii the iigur'e'.' If now'v a call is initiatedby K tary nonne ons wiil be nia-de iifith' nil of the steppinninanneti r2 etc. net however, being the ly' one htt'iinfg ground- Aennneenen, this ina-gnat .Wiiigbe the nnivpn eneigize'ci and will step its'switeii into connection `with the (falling41 subscibers y the" 'other is, 2s and ete; if'e' n iiiiii iinaifected; o' T1v trunkA 'noirespnniii' ing tn the switch S been inns placed tent so that @inmune isL cnnneeted with the (iroiind is thus nleeedunon vone sident the sten' infn inngnet 152 so that n'ponf a: succeed.; e'all freni sebseriber thel stenping" magnet n2 will'` be" energized'. as wasl the mag-tiet e2 and t`lie1switch 1S' Willbe4 stepped into position to connectie@ second nailing subscriber Wi'th the' trunk-eorresbonding to the siviteiiis. This". second trunk having been pinned in use, the arinatnie if of this trunk Will ina-ite a' grund *conneetion through its' fortvr'd Contact for' thearmeture 2" and stebnin' iiiariiet`l2s2 oi the' sue- (Leeding trunk alle this op ,rationof causing each trunk es it brought intol use to establish oneeti'onsfoii the bringing di asu'oeeeding trunl? into operattibn upon the initintinn @if ennui-er C9111; in ni-rieti ont to the* lirnit' nf the apparatus. y y

With the imifiietus thu vdesr'ibed iti Will be" seent'iiat if a stabbing inanfne-t 2S? is receiving" impulses through armatures' as' fr" and if of other trunks, and is stepping its sW'iteh 2s to eonneet its ytrunk' theleall ing;A subseribei', gend either or both of the trinis'th'rugh Wllioli the circuit otthenlalg# none of the trunks are in use, the arlnatnr'e `10o in use, sieeve relay" Rviwiii be energized and net 2S2 is made, is or are cleared out, one or both of the armatures 1^ and 1f will fall back and the circuit of the magnet 2E2 will be broken and the operation-of the magnet will cease, leaving the switch 2S in whatever position it happened to be and confusion of the apparatus might result. To avoid this, contacts a and b are provided for each trunk selector switch except the one having its steppingmagnet connected with ground through an armature of its own tr'unk. The .iechanical arrangement of these contacts is shown in Figure 7 which will be referredto hereafter; these contacts are normally closed but are separated when the switch is in zero position. One of the contacts is connected with the stepping magnet of its switch while theother is connected to the ground. The ground connection of the steppingrmagnet is broken `at these' contacts when the switch is in zero position but after the switch has once leftthat position, the ejround connect-ion of the stepping magnet is maintained through these contacts until connection isr established with the calling Subscribers line regardless of whether trunks, through which the initial connection for the stepping magnet was made, are cleared out or not. f

The trunk Wires 23 and 24 extend as shown'in Figure 3 to the side-switch arms .910 and 812 of the selectorv switch S2. VThis switch is of the Strowger type referred to in the beginning of my specification, having a main spindle arranged for both vertical and rotary movements, thisspindle being placed at the axis-ofl a set of contacts ar-y ranged-in ten rows of ten each. Carried lon the spindle are talking-circuit wipers s1 which co-operate with the bank contacts s18 and a test wiper s2 which cooperates with the multiple test contacts 822. The switch spindle is stepped up to bring its wipers opposite the desired row ofl contacts by means of the so-called vertical magnet o controlled t-lirougha relay V and the rotary inoveinentof the switch is brought about by means of a vibrator magnet o which makes and breaks its own circuit as it vibrates and is controlled by the relay T when the side switch arm s3 is in its second or interinediate position. It is unnecessary to give here any extended description of the circuits and apparatus of Figure 3, all of these ybeing old and well known to those skilled in the line contactsin its banks arranged in rows of ten each. `The spindle is stepped up to bring the wipers S24 opposite the desired row by means of a so-called vertical .magnet {z r and is rotatedstep by step by means of a so called rotary magnet o2, which in this case is nota if'ibrator but responds to distinctive current impulses, since the desired .line is identified with a single pair of contacts only. and therefore the row of contacts must be `selected and the pair of contacts in the row afterward` picked out by the wipers, before testing. In this resides the principal dif- 'erence between. the connector and selector switch, the purpose of the selector switch being to pick outrand connect with au idle trunk line in any desired group. In the operation of' the selector switch, therefore, the

spindle is stepped up by means of definite and distinctive impulses to the row of con tacts S13` and 322 representing the desired group (which may be either thousands or hundreds and ,in this caseis hundreds), and after that, when the side switch has taken one step, the rotary magnet o takes control of the switch` and steps the spindle around continuously as long as thewiper S20 findsv condensers CV for the reason that the for-v wardiinpulses which work the` switch must notbe confused by the battery current' supplied to the called subscriber. We may assume that the switches of Figure 3 are both in thefsanie building with the apparatus of Figures l and 2 although this is not at all necessary, and'in such case they battery B shown separate in the two figures is of course vthe same battery.' p of supplying talking current to the called subscriber. I connect this battery tothe sleeve conductor 44 of the connector switch through a relay R8. and I ground the tip conductor 43 through the relay RT which is the saine as connecting it'back to 'the battery. Thus, the main battery is also bridged across the conductors '43 and 44 throughtlie relays Bland RVS which as in the case of the relaysR yand R in Figure l are wound to approximately ohnis each," but present high impedance to voice currents. R9 is the ringing relay, which controls the application of the ringing generator to the called line and is itself controlled on the one handby the relay R10 and on thefother by the com inutator K, which may be common to all the ringing relays ofthe exchange.y The circuit of the ringing relay is indicated at this ungrounded or `idle For the purpose lll) contacts vconnected with ,the trunk which has been connected up with the calling subscriber, when the switch S is stopped.

After the operator has performed her functions and the connection through the trunk a call upon a trunk, interlockingmeans between these switches is employed and this 1s shown as consisting `of interconnections similar to those employed for preventing more than one of the trunk selector switches from being started up by a singleV call. Re ferring to Figures l and 9, itwill be seen thatthe interrupter I connects the 'stepping magnet R2, with the back contact of the armature 2m of the relay R11 and that armature is connected with battery. The front contact of the armature 2r of the relay 'R11 is connected with the corresponding armature of thecorresponding relay of the next operators set and in turn the front contact of this last armature is connected to the corresponding armature of the next operators set and so on tothe limit of the apparatus. It will now be apparent that when a trunk is connected withaa calling subscribers line,` if all the 'operators sets are idle, the set having direct connection with the battery will have its switch S stepped into. connection' with the calling trunk. If this operators set is busy, the circuit to the stepping magnet of the next set willrbe closed and the switch of thatset be stepped into 4connection with the; calling trunk, and/similarly connections to the stepping magnet of the next trunk will be established if the set last previously` mentioned is busy. .Thus when several oper# ators sets are simultaneously used, they are successively thrown into operation progressing from that set directly connected to .bat-` tery to the limit of the equipment.

yIt is torbe observe-d in connection with the interconnections of the operator-s sets asjust set forth, that ifa set or sets are busy, and connection throughthem has been made to another set, the selector switch of which is being stepped to make connection with the calling trunk, and one of the sets through which connect-ions are made is cleared out, the circuit of the stepping magnet of the switch being stepped will be broken and the switch will be left in whatever position it may happen to be and may `cause confusion in the apparatus, unless means are taken to provide against it.V To this end contacts a2 and b2, the mechanical arrangementr of'which is shown in Figure 5, are provided at each operators selector switch except that one which has its stepping terasse magnet controlling armature connected directly to f battery. `These contacts are no1* mally opened by the switch when it is in zero position, but are closed at the initial movement of the switch. One of the contacts is connected to battery while the other f a circuit has been established for the stepping magnet of an operators switch, that circuit will be maintained until the desired connection has been established by said switch regardless of whether operators sets, through which the stepping magnet was initially connected, are cleared out or not.

Referring lto Figures 1 and 9, to illust-rate,

and assuming the operatorsset including vthe relay R11 to be busy and therefore that relay to be energized, the armature 2m will come against its forward contact and close the circuitof the steppingmagnet of the next operators set. It will now be apparent that if the relay R11 is deenergized, its armature 2F11 will fall back, breaking the circuit, at that point, of the stepping magnet of the next set, but the circuit of that magnet, if its switch has been moved from its zero position, will be made through contacts a2 and b?. IVhen, however, the selector switch of this second Vset has established connection with the calling trunk, thevcircuit of the stepping magnet will be broken by a relay 4of its yown set and the switch will stop. l

In the lower part of Figure 2, I have shown the apparatus which appears in front of one operator, consisting of a set of buttons only. Above these in the figure, I have ,shown a set ofl wheels or sections of a drum with'the co-operating springs, the motor and the common commutator of the central office sending, machine. This machine furnishes the impulses by which the selector and connector switches are worked in order to select the line wanted, and the uu'n'iber of impulses sent as well as their arrangement is determined by means of the operators keys or buttons. These keys are in three KA K and K2, each set having` ten buttons controlling contact springs c, 7a2. The springs 7c of all the buttons in each set are'joined to a common wire, and the ends of these three common wires are connected together at the point 70X, from which point the conductor 70 leads, as shown in Figures 2 and 1 to the wiper contacts e30 in the switches S. The spring 7a2 of each key is connected to a pen on the appropriate disc or Zone von the sending machine drum. When any particular button is depressed, therefore, it connects its individual wire to the common wire 7 0.y The individual wires Maese@ of the keys K are marked respectively 71, 72, 7e, 7i, 75, 76, 77, 78, 79, so. similarly the individual .Wires `trom the keys'l are marked 8l, 82, 83, 84 85, 86, S7, 88, 89, 9,0, and the individual Wires of the keys K2 are marked.` 91 92, 93, 94, 95, 9,6, 97, 98, 99, 100. The sending; machine comprises trie main commutator D, having a brush al' connected to the main battery, and riding over its segments so as to produce regular renin-ring makes and breaks in a. continu@` series. In practice this commut-ator is made 'with a pair ci? spring; contacts and teeth or cams are formed on the body ot the commutzusor to work these springs up and down, but for convenience ot illustration I have shown the .brush resting` directly on the periphery of the disc. l/Yith such Va construction in actual practice and considering' that. this commutator will carry a. large number ot switch ing impulses simultaneously, I prefer to make the brush d ot carbon. This is a detail, however., whichv may be varied at vvill and does not affect the invention. The cem i mutator l) is graphically shown as carried on shaft do which extends through all of the numberivlieels formino; both the. mechanical and electrical connection thereivith. The mechanical comiection is not shown in the drawing but the electrical connection is indicated by a wir@ marked do. The number Wheels are shown at d, d2, cl3, di, d5, d, 17, als, dg, d10, each 'having a tooth or raised segment ot a suitable length Lto l.cover thespace ot the number ot teeth on the Kcommutator equal to the number ot impulses particular Wheel is to transmit.

Thus the first ivheel d has a single tooth du,

approximately equal in length to only one tooth on the main commutator. The second Wheel has Ia single tooth 412 approximately 4,egual in length to tivo teeth on the commu tator, and so on.` In other Words, instead ot using ay set of number Wheels each `ot which makes and breaks through a number teeth, I have all the makes and liireaksI on the main commutator, Aand in order to send any desired numher ot impulses, I select a wheel which Will maintain connection` With ythe commutator While the desired number ot impulses are being* produced and are then cut oli?- theretroni. Another peculiarity ot arrangement is that the makes and breaks on the number Wheels el', d2, d?, etc., aremade during the passa, 3 ot gaps on, the main cgmmiitatorivhen there is Zero, potential, and hence there will be no sparking` atthe number Wheel contacts. In order to do I i 'ay either subdivide thercommutator surface evenly and equally into alternate conducting l and insulating segments and then make each number Wheel ltooth slightly longerthan that of .the particular toothto which it corresponds, orI may make the tendiente minors 011 tbeeomniititof smaller than the insulating` portions and the number Wheel teeth ot lengths equal to thc enactA multiple of a unit sulfuilivision.- p Y l Itwill be observed that there are teur sets of pens on the number Wheels. ,lhese will accommodate tour sets or keys K', K2, etc. It a. greater number of digits appear in the numbers to be transmitteth `the Wheels must be provided With additional sets ot springs. The set K has its individua-l Wires connected to the first set ot springs 0513,the set K has its individual `Wires connected to the` set ot springs dlt, and the keys K2 are similarly connected to the spring pens d1?. The generalv direction of rotation `ot theconnnutator. and the various Wheels con,- neeted to it is clockwise as shown by the arrows in Figure 2, and the teeth on the Wheels come into contact .vith the sip-ring pens in theorder 0513, CX14, d1?. Thus the number set up on the set of buttons K is transmitted over the Wire /O iirst, then tollo-vvs the number set up on the buttons K, and so on.'y Thus `tor thenumber 468 the operator would depress Ithe fourth button in the set K, the sixth button in the set K and the eighth button in the Set K2- Br tracing the `circuit-s it Will be found that When the controlling` circuits are closed, which occurs at the beginning of a rotation when the wheels are all in the position shown in Figure 2, current will pass from the main battery to, the commutator D,

thellCe to the Wheel cthence by Wire 941u to,` the toiurth key ini the set l( and thence to the. lWire 70' and so on to4 the Wire 19 and the relay R5 in Figure l., Wl'iich repeats the impulses over trunk Wire 23 to the switches. Ars the Wheels continue their rotation, this circuit will be broken atten tour impulses have been transmitted, and then a. nevv circuit Willbe formed Carrying current* from Vthe battery through the commutator to the sixth ivh eel al, and thence from 'th e second spring dit on that Wheel through the wire to therkey which is closed, thence to :the Wire TQ and thence again to the. relay R5 which repeats to the switches. After these impulses .have been sent by this route, this circuit will be broken and av neuT circuit will be formed irointhe` main battery through the Coininutator l) to the eighth Wheel to the third pen thereon, d1, then-ce yto the eighth key in the setl K2, which has been, closed, thence to Wire and t0 the'relay R5 as betore.v The closures betweenthe Wheels and successive set-s otsprings are arranged to be separated by intervals, during which no vciirrent at all tlovvs to the Wire 70. These intervalsv are` necessary in order to permit thesvvithing circ/tilts to be rearranged so as to produced the, proper results in Vresponse to; e, successive lsets ot Working impulses. 'la either verde termes/hewn herein a, Set

of Strowger switches, I must provide not V only the vertical or working impulses in groups, but I must also provide the interposed or rotary impulses between said groups. This is accomplished by means of the wheel d, which has -four teeth set 1n quadrature, and all adapted to make contactV with the single pen cils, which is connected by the wire 170` to the wiper contact 829 of the operators selector switch S, and thence through the wire 20 to the relay R, which repeats the rotary impulses over the trunk wire 24C to the switches. The wheel d is insulated from the shaft Z0 and is grounded through the wire 101, this being necessary because the relay It is connected onits other side to battery wire 3. In other words, the repeating relay R5, which is controlled by the number wheel, is a grounded relay and so the number wheels take battery impulses from the commutator to work it; but the relay RG is on battery, hence the rotary wheel ZU uses the ground to work the relays. 'Ihe reason I make one of these re lays grounded and the other to battery, is in order to pull them both up simultaneously when the operator has her telephone set bridged across the wires 7 0 and 170 in Figure 2.

I-Iitherto the selector switches referred to as S and S have been referred to only as regards the electric circuits and cont-acts with which they are associated and in this connection the diagrammatic illustrations in Figure l have been sufficient. The mechanical features of a switch adapted to perform the functions of the switch S of Figure l is shown in Figures 5 and 6. This switch comprises a frame on which is mounted a bank Z) of contacts consistingof ten rows of contacts of three contacts each. VThe contacts of the different rows are adapted to be successively engaged by Ywipers c, d and e which are fixed upon the rotatable shaft f, the three contacts c, d, and e being respectively insulated from each other. A spring g interposed between the shaft yy and the frame tends to move the shaft toone limit of movement, when the contact arms carried by the shaft will not rest upon any of the bank contacts as shown in Figure 5. Fixed upon the shaft f is a ratchet h. The teeth of the ratchet are so constructed that a pawlV engaging therewith will prevent movement of the shaft under the influence of the spring g. Adapted to engage with the ratchet h are a holding pawl z' and a stepping pawl k. The pawlz' is pivoted upon the frame and its nose is normally held in engagement with the ratchet by means of a spring Z. The pawl .7c is pivoted to the armature mzof the stepping magnet R2, which armature is in turn pivoted to the frame of the magnet or upon any other suitable stationary portion. The armature m2 is normally held retracted by a spring 0 while'the nose of the pawl 7c is thrown outwardly by means of a spring p extending between the armature m2 and the tail of the pawl k, yThe outward movement of the nose of the pawl 7c is limited and it is' guided in itsgmovements by a stationary pin g3. VIn order that the. holding pawl z' may be disengaged from the ratchet 7L so that the contacts upon the shaft f may be returned to their normal position under the influence of the spring g, a magnet S33. known yas the release magnet is provided. The armature s3 of the release magnet is retracted by means of a spring t, this armature being limited in its outward movement by a nut a in screw-threaded engagement with a screw v3 mounted upon the frame of the magnet and extending through the armature s3. @bvieusly the nut a is capable of adjustment along the screw o to permit greater or less movement of the armature s3. Carried by the armature s3k of the release magnet is a resilient arm lw which carries a ratchet tooth fr adapted to engage with the lower end of the holding pawl i. An arm y mounted upon the armature m2 of the stepping magnet overlaps one end of the arm 'w and is adapted to draw down one end of that larm so that the lower end ofthe pawl z' will clear the tooth m when the armature of the stepping magnet is attracted. The operation of the apparatus is as follows: Assuming the parts to be in position as shown, as impulses are supplied to the stepping magnet its armature will be attracted a number of times equal to the number of the impulses and at each attraction the pawl 7c will be thrown forward into engagement with the ratchet wheel and will move that wheel forward a distance depending upon the adjustment of the various parts, which are so adjusted that at the first impulse the wipers upon the shaft f will be moved into engagek ment with the first row of bank contacts and will be moved to a succeeding row upon each impulse thereafter. The shaft and wipers which it carries will be prevented from retrograde movement by the holding pawl which is forced into engagement with the ratchet h by its spring. A desired row of thebank contacts having been reached in the manner described and the object for which the connection was established having been accomplished'7 it becomes necessary to return the wipers to theirv zero or n ormal position in readiness for another operation as vjust described. This restoration is effected by deenergizing the release magnet 833, it having been previously energized, when its 'armature will be retracted, drawing the tail of the holding pawl 'L' with it, and the nose of that pawl will be disengaged from the ratchet h and the wiping contacts will be returned to their initial position. In the next selective operation of the switch, however, it is necessary that the holding pawl z' shall engage with the ratchet iz. to hold the contacts in anyposition to which they may be' stepped. It, therefore, becomes necessary to' release the pawl c' from the arm prior to the succeeding stepping operation. This is accomplished by means of the arm y/ which upon the rst energization of the stepping magnet and the attraction 'ot its armature, will draw down with it the -ree end of the resilient arm fw, thereby -fre'eing the pawl z' whereupon its nose will be thrown against the ratchet z) by the spring Z. The contacts c2 and L2 operated by the projection e are normally closed, but in the zero position of the switch are separated bythe projection eras shown.

It will be noted in regard to the switch just described that theV release of the wipers occurs upon the deenergization' of the release magnet, the holding pawl being in position to engage the ratchet and restrain the wipers so long as the release magnet remains energized after having once `been excited. It may be, however, that it will be of service for the release of the wiper contacts to occur upon energization of the release magnet and for the holding pawl to be disengaged from the ratchet even tliough the release magnet may be deenergized. Such a condition arises in connection with switch S. A structure adapted for operation in this mannerbut inv other respects like the switch just, described is shown in Figure`7. On reference to this ligure, it f will `be vseen that the holding pawl z" is pivoted at c and its nose is normally held in engagementV with the ratchet by the spring 6V. The tail of this holding pawl is adaptedv to be engaged by armature s3 of the release magnet s". Vhen this release magnet is energized, its arma ture is attracted and the holding pawl z" is moved against the spring d so that it 7 clearsthe ratchet, when the wiper contacts are `free to return to their :initialr position. Then the armature s3 is attracted, it carries with it the resilient arm lw', the tooth m2 of which latches behind the stationary detent St. The holding pawl is thus locked away from the ratchet until, at the first impulse in the stepping magnet s2 lat the beginning of another selective operation the arm y is drawn downwardly and unlocks the arm fw from the stationary detent, whereupon the holding `pawl comes into engagement with the ratchet. The roperation of: this switch is4 in all respects similar to that. of the switch in Figures 5 and 6 except as to the releasing means above indicated..

The operation of the system can `be best set forth by tracing the connections and noting the operations. or the various partsthe time a call yis initiated atl the subscribers station until tlieconversation has terminated and the apparatus has stored to its normalcondition.l 1

Let it be'assumed that a subscriber ata station as A desires to converse. moves the receiver from the hook when the latter rises and establishes la connection,

been rethrough his transmitter and receiver, 'be

tween the lines 1 and 2. A `circuit isthen established from the free terminal oliIV the battery B through the wire 3, vline relay M, armature n, line 1, subscribers set, line V,2 andfarmature n to ground. The relay M, being lthus energized, attracts its armatures m and m, va circuit then being established from the tree side of the battery B throughv conductor 3, interrupter I, armature `mand conductor 8, to conductor 31 whence the circuit passes to one of the stepping magnets as s2 of the trunk selector switches as before explained. From the stepping m-agnetthe battery conductor 3. From they wiper 14 circuit is made through conductor 27,- make*- before-break contacts 28 and 29, conductor 30 andvrelay N to groundf The relay N being thus energizedv attracts its armaturesl 1 andv 2* and connects the"'trunk conductors 17 and 18 with the trunk extensions 15 and 16 which are connected to the wipers 12 and 13 respectively.` Y

When the wiper 14 rests onthe contact Y 11, the wipers 12 and 13, rest on the contacts 9 and 10 respectively. is therefore connected in series with the relay R" in a circuit which can be traced He 'res i The cuteot relay N circuit passes through the conductor 8V and -the armaturer of the relay R" to ground.

ythe armature m which is connected tothe from the ground through relay N, eXtension 5, contact 1O,fwiperV 13, extension 16, armature 1,trunk wire 18 and relayrR to the free` side of the battery. The relay AN` is of high resistance `compared to thatof` relay R and R and operates on less current so'that While the relay N vis operated, the relay R is notI operated by reason of the circuit just traced. VThe relay N, however,

is of' such resistance that it will carry sufiicient current, after the relay R' is'I con-` nected', `to hold its armatureslafter they have been attracted.V The relay N being thus energized, attracts its armatures-, thereby breaking the circuit of the line relay at the armature nwhereupon'the rel-ay MA is deenergilzed and its armatures fall backI thereby breaking the circuit* of the stepping magnet s? whereupon the switch'stops. The attractions .of its armatures by the relay' N, connects the subscribers lines 1 and 2 ywith the eXtensions4-and 5, contacts y9 and 10, wipers 12 and 13,trunlz extensions 15 and 16, armatures 2n' and 1 and trunk conductors 17 and 18 respectively. It will now beseen that the tip and sleeve relays R and R' are connected by means of the ,connections just traced, in series through the subscribers instrument and between battery and ground.

The relays R and R being energized, their armatures will be attracted, whereupon e the circuit ofthe .release magnets will be broken atjthe armature? and the armatureV Y their `back contacts thereby ,breaking the battery connections which otherwise would be established with the trunlr conductors 21 and 22 upon the attrjaction'of the arma- Y ture 2r? of the relay R4. The armature r of the-relay R' on being attracted, leaves its back contact andthus breaksjthe circuit throughthe steppingmagnet s2 and, coming against its forward contact, makes ground connection, through conductor 41 for the stepping magnet 1S,2 of the next trunk selector switch as before explained. The attraction of the armatures 1r and 2r yagainst their front-,contacts results in the establishing of ground connections through the wires 42r and 43 with the armatures rt and 1r4 of the relay R4, .and also with one terminal of that relay.

Circuit may now be traced from the ground `through the armature 2", conductor 48', armature l, conductor 44', stepping magnet R2, interrupter I'.conductor 45', armature 2r11 and its back contact and conductor 46 to the battery wire. The magnet a2 being intermittently.energized will reciprocate its pawl, (see Figs.` 5 and 6 and descriptionsthereof) stepping the 'switch forward.` Vhen theV wiper 831, rests upon the contact s3 circuit may be traced from the ground through armature 1r', conductor 42', armature 114,-conductor-48", contact s3,

wiper S31, conductor 49', armature 1m,con

. d-uctorV 50 and magnet R114; tobattery. In

coming against its front contactth'e armature `2F11 establishes connection for the'stepping magnet of the next operators selector switch as'hereinbefore described.

The attraction of the armature r against its front contactcloses the circuit from the ground through-relay R5, conductor 52', conductor 19, contact 35, wiper` .930, conductor 53', 'armature r, conductor 54', vmake-before-break contactsv 5.5'V and 56', relay R11,

vhas been momentarily energized and that its armature fr5 has been momentarily brought against its .front Contact, thereby momentarily closing the circuit of the relay R4v from the ground through armature 2f', conductor 43', relay R4, conductorS, conductor 59 and armature rito battery.l The relay 1 4 is then energized and attracts its armatures, the armature 2, coming against its front contact and locking battery connection on the relay R4 so .that its circuit is maintained `after the relay R5 has been deenergized. The attraction of ,the armatures r4 and. 1r4 breaks ya portion of the current passes by light L to ground and the other portion passes through release magnet 833 to ground. The release mechanismis thus set to engage the holding pawl of the switch S (see Fig. 5) and the operator is notified of a call by the lighting of the lamp. Y v Connection mayl now be traced from battery through relay R, conductor 20, cou-4 tact S34 and wiper S2 to conductor 170. Connection may 'also be traced from ground throughrelay R5, conductor 52', conductor 19, contact 835, wiper 830, conductor 53' and armature fr toconductor 7.

' Referring now to Figure 2, it Vwill be seen that the conductors 170 and 70 are adapted to be connected by means of the pressure of a'buttonA O with the conductors 127 and 128,l

whichlead to an operators set of usual construction and hence not shown. It will be seen that upon the depression of the button O, that a-circuit will be completed from the battery wire-at one side of 'the'relay R through that relaythe operators set, and

the relay R5 to ground. iTallring current the operatorsfconductors 2() will .be con.

nected with the trunk conductor 21 while the other voperators conductor 19 will be connected with the other trunk conductor 22. It will now be apparent that the op sumed that this number is 468. The operator depresses the fourth key of the set K7 theV sixth key of the set K', eighth key of the set K2. In this manner the conductors 941, `86, and 78 are connected with the com-` mon point 70X, these conductors being respectively connected with the pen Z13 of the drum section d4, the pen 0114 of the section d and the pen 15 of the drumsection d8. The commutator Dy is driven rby amotor M,3 and, the motors-upposed` in the particular apparatus shown to be normally at rest, it becomes necessary to start the motor and commutator.. To accomplish this, the operator depresses the button O and thereby connects the conductor130v, which'is connected to one terminal of battery to` the conductor 131 and thence through the conductor 132 tothe relayR12 vand to ground. The relay R12l being thus energized, its ar` matures?"12 andl,2 are attracted when circuit will be closed from the battery wire 109 through the lastmentioned armature, conductor 133 and relay R13 to ground. The

Y relay R13 being thus energized willattract its armatures 7413 and 1113.` The circuit of the relay R11 to battery through the armature 713 is thus brokenbut this connection is `made through the armature r1 of the relay R12 whereby the control of the relay R11 is transferred from the relay R13 to thel relay R12. `Circuit may be traced also 'from the motor conductor 134 through the armature 1T13 and a suitable generator and ai motor starter as indicated which may be of any well known type to the other motor conductor 135. The motor will thereupon start up and place the commutato-r in operation. There is also set in operation a startingrdisc (ZS which is of conducting material with the.

exception of insulating segment 136- upon which the-pen 137 normally rests. After the motor and with it the commutator, starting disc7 rotary discvand drum sections are set in operation by the depressionof the key O', as described the pen 13.7 will ride off the insulating 4segnnent and maintain the circuit initially closed by the depression of the button O. This circuit being closed the motor, commutatorand diskswill continue to revolve j until the pen 137 again rests upon the insulating segment 136, when Vthe circuit will be ybroken and the apparatus will stop. During this rotation,l first the pen Z13 corresponding' to the disk Z4 will be engaged bythe contact `segment upon the said disk, which is ofvsuch 'a llength as to maintain the Contact with the `pen during four impulses of current through; the commutator.V The circuit ovei which these impulses are sent,l may be traced fromV one terminal of the Vbattery to the brush l thence through the commutator, the conductor Z111 tothe shaft of the drumgthence vthrough the drum to the segment of the disk d4, the pen CX13, the .conductor 94, the contacts of the fourth button of the row K to the point 7c,"v thence through the conductor to the contact s3 of theswitch S",co.n

of the `four impulses, the relay R5 will be energized and attract its armature 2.11 against its back contact connected with the battery B. At each im-pulse,. therefore, the tip side '23 of the trunk will be connected withbattery andthe impulses willbe', repeated over this side of the trunk toop erate'the. automatic selector and connector switches as before described the next operation consists of the sendingo-t a rotary ductor 19 and relayv R1V toI ground.' At each impulse, occasioned by the coming `in conc tact with the pen 18 of one of the conductf ing' projectionsv upon thedisk d"- This action causes the closure of a circuit from the ground through a conductor 101 disk d, pen 0318, conductor 170,` contactrsi, of the switch S', conductor 20, and the relay R6 tothe battery wirey 3. Each projection on the disk d is of such length as totransmit but onelimpulse and this impulsepass.- ing through the relay RG through ythe circuit just traced, the relay last mentioned attracts its. armature 1r6 against its back con-- tact ythereby connecting the `sleeve side 2,0 of the trunk momentarily with the battery wire, when a` rotary impulseA isV transvmitted over ythe sleeve side for working the side switches of the automatic. selector and connector switches as before indicated; after the sending of lthe rotary impulse as described, the conducting segment of the disk d comes in contact withits pen du. Then six impulses are sent over the conductor 86 to the point'c",whencecircuitis thesame as before,` through the relay"R5 and six vertical impulses are transmitted over the tip side 23 of the trunk. The disk d1? thenV sends another rotary impulse over` the sleeve side of the trunk as before yand eight vertical impulses are then transmitted over the tipy side byrea'son of the contact upon the disk` dgcoming in contact with its pend, connected with the conductor 7 8 through which connection isi established to the point k", the circuit being otherwise the same as before through the. relay R5; This is fol-- lowed by the sending of'a rotary impulseby the `disk d and then the apparatusx-is brought to a stopv by reason ofthe. pen 137 riding upon the insulating segment 136. Y At the close of. the operation just described, thek wanted subscribersline, Vunless it is busy, will have been connectedA asbefore described. The entry of the pen 137 upon the insulating segment 136 at the 'endof the connecting operation breaks the circuit as before traced through the relay R12 which thereupon `releases its armature thereby breaking the circuit ot the relay R11 which in turn releases its armature '2F11 thereby breaking the circuit` of the release magnet 333 when (see Fig; l5) the holding pawl z' will have its noseremoved from engagement with the ratchet uponl the switch shaft and thejswitch Vwill return to its 'zero'positiom thus leaving the operators setidle in readiness to perform the connecting' operation 'for another connecting trunk and its subscribers instrument. llhe Ycircuit of the relay R13 will be broken fat the armature 112 whereuponthe motor circuitlwill be broken gatthe armature 1*"13. n Connection having lbeen established as described, between two stations, the hangingup of the calling subscribers receiver 'breaks the circuit through the relays R and R whereupon the former releases its armatures which fall against their back contacts. The armature fr connects the release relayv s to battery whereupon the holding pawl-is retracted from the ratchet on the Aswitch shaft and the switchreturns to Zero. The armatures 2r and 3f, respectively, )place battery on the trunk conductors 21 and 22 simultaneously.' This results in the simultaneous energizationof the relays'V2 and V3 ythe circuit of the relay V2 being traceable from the trunk conductor 43 through relay `V2 and conductor to ground while the ,circuit of the relay V3' is Vtraceablefrom the trunk conductor 44 through the relay V3 v'to' ground; Relays V2 and V3 having; been thus energized and their armatures attracted, circuit may be traced from the battery wire 52, release lrelay QI, conductor 53, conductor l64, bank contact 822, wiper 820, re lease relay Q, conductor 38, side switcharm 814 and conductor 39 to ground. v The release relays Q, andQ being thus energized: will attract their armatures when the cir cuits of the release magnets gandg of the switches S2 and S8, respectively, will be closed whereupon those switches will be released 'and will return to their normalpositions. l

The breaking of the circuit ofltherelayA R through the relay R4 does not cause the release oi" the armatures Aof the latter pas" its circuit is maintained through the Acut-j ofi1 relay N, sufcient current iiowing to hold the armatures, aitter theyhave' been attracted.- Upon the restoration ofthe switch Showever, the circuit oftherelay' Re throught-he relay N, willv be broken" and the armatures 'will fall back, armature 2r .breaking thecircuit ot relay R4 whereupon yits armatures willl iiall back and the appasubscribers.- Y

Having thus described my invention what I claim andv desire to secure by :Letters Patent is:

ratus is then in readiness to connect other 1.- In a telephone exchange system, a numtrunks, all of the switches speciedbeing normally' in a zero or inoperative position,

and adapted to 'be started Vupy to test and connect with bank terminals-in theirnumerical order, substantiallyas described.

2f. In a telephone exchange system, a number of subscribers lines, a number of trunks les's than the number of lines, each trunk terminating at one end in a primary selecl` tor switch, and at the other end in a first selector switch, an operators-circuit and ap` paratus including atelephone'set and a' send-L ing device, and anVK automatic switch associated withV the -operators'circuit and containing terminals `of a vnumber of said trunks, together with release or restoring means llforall of said switches, substantially as described.` v

3. In a telephone exchange system, a number of subscribersflines, a -number of trunks less than the vnumber of lines, leach trunk terminating at one end in a primary selector" switch, and at' the other end in a first vselector switch, an operators circuit and ap'- paratus including a' telephone set anda sendingdevice, and an automaticswitch associated with the operators'circuit and containing terminals of -a number of said trunks, togetherwith driving means for the primary selector switches controlled by theI` calling subscribers, and driving means for the operators switchescontrolled by theprimary selector trunks, lsubstantially as de-l scribed. 'n g 4, In atelephone exchange system, a num-Y berof subscriberslines, a number of trunks less than the number of lines, each trunk terminating at one end inaprimary selec# tor switch, and at the other end in a first selector switch, anl operators circuit Aand apparatus including 'a telephone set" and a sending device, and 'an automatic switch asso'ciated with-the operators circuit and containing 4terminals Lof a number of said trunks,-togetherwith drivingmeans and release or restoring means for the primary selector 'switches' controlled by the, calling subscribers, and driving means for theV op# terminating at one end in a primary selector switch, and at the other end in la first selector switch, an operators circuit andy apparatus including a telephone set and a sending device, and an automatic switch as# socia-ted with the operators circuit and containing terminals of a number of said trunks,

together with driving means and release or' restoring meansfor said primary selector' switches controlled by the calling u subscribers, and driving means and release or restoring means for the operators or secondary switches controlled in the use of the primary selector trunk, substantially'as de# scribed. 4

6. In a telephone exchange system, a'number of subscribers lines, a number of trunks less than the number of lines, each trunk terminating at one end in a primary selector switch, and at the other end in a first selector switch, an operators circuit and apparatus including a telephone set and a sending device, and an automatic switch associated with the operators circuit and containing terminals of a number of said trunks, together with driving means and release or restoring means fo-r the primary selector switches controlled by the calling subscribers, driving means and release or restoring means for the operators switches controlled in t-he use of the trunks, and driving means for the forward or calling selector switches controlled by the operator, substantially as described.

7. In a telephone exchange system, a number of subscribers lines, a number of trunks less than the number of lines, each trunk terminating at one end in a primary selector switch, and at the other end in a first selector switch, an operators circuit and apparatus including a telephone set and a sending device, and an automatic switch associated with the operators circuit and containing' terminals of a number of said trunks, together with driving means and release or restoring means for the primary selector switches controlled by the calling subscribers, driving means and ielease or restoringV means for the operators switches controlled in the use of the trunks, driving means for the forward or calling selector switches controlled by the operator, and release or restoring mea-ns for the said calling Vvselector switches controlled over the lines rality of subscribers lines, a number of trunks less number than the `4number of f lines,l an operatorsucircuit `including a' telephone Vsetand animpulse" sending device,I

means for automatically connecting a calli ing line V"with any one of said trunks, there by rendering the said trunk busy, means for automatically connecting the operators send-` ing device with said busy trunkand means for automatically connect-ing said trunk with a wanted line. i f

9. Ina telephone exchange system, sub--` ,scribers"lines, aV number ,of trunksljess than the number of. lines, an operators'impulse sending device, means for v'automatically connecting a calling line witha trunk,'meansl thereupon becoming active for automti# `callyv connecting the operatorsl sending' 'device with the busy" trunk andfautomatic switches forconipleting the ,connection to aj wanted subscriber, said switches being con` trolledmby` impulses froinfthe" V-operators' sending device, together with `restoring means for the connecting means.`

10. A telephone system including a call#90 an exchange, a central loffice 'link-circuit,:

ing subscribers line, terminals therefor at adapted to beautomatically connectedwith said line on initiation of a call, an voperatorsA position, a'trunk lineleadingthereto', a'sifg v nal for said trunk line, an electrically con-- trolled selective switch at the exchange, means for initiating travel thereof to connect said link-circuit and trunk line in response to the operation of said selective switch, a called subscribers line, terminals therefor at the exchange, operators means for transmitting directive currents over said trunk line to establish a connection from the terminals of the calling line to terininalsof the called line, with means for thereon freeing said trunk line.

11. A telephone system including a calling subscribers line, terminals therefor at an exchange, a central oiiice link-circuit, adapted to be automatically connected with said line on initiation of a call, an operators position, a trunk line leading thereto, an electricallyy controlled selective switch at the exchange, means for initiating travel thereof to connect said link-circuit and trunk line in response to the operation of said selective switch, a called subscrihers line, terminals therefor at the exchange, operators means for transmitting directive currents over said trunk line. to establish a connection from the terminals of the'calling line to terminals of the called line, with means for thereon freeing .said trunk line.

12. A telephone system including a calling subscribers line, terminals therefor at an exchange, a central otlice link-circuit, Y

adapted to be automatically connectedwith said line on initiation of a call, lan operan 

